Applications of Various Thin Film Deposition Techniques for Oxide Dielectrics, Metal Interconnects and Polymer Insulators

Abstract

As the feature size gradually approaches the physical limit, the downscaling of the semiconductor industry guided by Moore’s law has encounter many challenges. However, recent advances in thin-film materials and deposition technologies have enabled a broad range of technological breakthroughs in several areas. In this thesis, various thin film deposition techniques such as Chemical Vapor Deposition (CVD), Atomic Layer Deposition (ALD), Direct Liquid Evaporation (DLE) CVD and Molecular Layer Deposition (MLD) for different materials and applications are discussed. An epitaxial MgxCa1-xO gate dielectric deposited by ALD are achieved on GaN, showing excellent dielectric property and crystallinity. The relationship between band offset and interfacial properties has been established with various ratio MgxCa1-xO/GaN. Nanocrystalline DLE-CVD Co with highly controllable growth characteristics and saturation growth was achieved at 200 oC. Based on capacitance-voltage (C-V) characteristics on samples with and without Co encapsulation, our DLE-CVD Co can effectively prevent the diffusion of Cu and serve as barrier layer and all-around encapsulation layer. On the other hand, newly synthesized volatile gold(I) and silver(I) bicyclic amidinates enabled conventional CVD of noble metals. Silver and gold films with good purity ~ 94% and low resistivity (an order of magnitude worse than bulk metal) were obtained at substrate temperatures below 230 °C, showing great potential of replacing Cu interconnect in complicated structures.

The molecular layer deposition (MLD) process of tris(2-aminoethyl) amine (TAEA) and pyromellitic dianhydride (PMDA) copolymer was developed. The TAEA-PMDA film grown at 170 °C was fully imidized as-deposited and showed great mechanical strength and insulating property through nanoindentation and I-V tests.

ALD and pulsed CVD deposition conditions for Hf3N4 and Cu3N were optimized. A metal dielectric photonic bandgap multilayer structure (MDBPG)- (50 nm Hf3N4/3 nm Cu3N/50 nm Hf3N4/3 nm Cu3N/ 50 nm Hf3N4/3 nm Cu3N/ 50 nm Hf3N4/300 nm SiO2/Si) was fabricated and the structure was confirmed microscopically and compositionally by TEM and EDS respectively. Preliminary reflectance versus wavelength measurements confirmed optical oscillations form the MDBPG and further investigation can be conducted on the configuration and thickness of our multilayer structure.